This invention relates generally to apparatus and methods for preparation of animal feed, and more particularly to the preparation of animal feed by pelletizing, including conditioning of the feed before pelletizing.
The presence in food of pathological bacteria is a matter of serious concern. Meat and farm products are particularly at risk, especially poultry and eggs. At each stage in the food chain every attempt has been made to kill bacteria and prevent reinfection. Salmonella are probably the best known pathological bacteria associated with food but other bacteria such as E.coli can occur and produce food poisoning to different degrees of severity.
An important link in the food chain is the manufacture of animal feeds, and it is essential that manufactured animal feed be free from harmful bacteria. Currently, there are a number of methods of killing bacteria in animal feeds with varying degrees of success. Some methods have the disadvantage of destruction of vitamins, others have the disadvantage of high power requirements and high capital costs. Most methods of bacterial kill involve heat and moisture, and provided the correct temperature and retention times are used, the bacterial reduction or kill is effected. Most of the systems involving heat and moisture are situated in the process immediately before the pelleting process and replace the conventional meal conditioning systems.
Typically, the steam used for conditioning and sterilizing is produced from a steam boiler or a vapor generator. Such machines are common and are applied in many industries. To a greater or lesser degree, the systems effect the condition of salmonella in the processed feed. This is accomplished by the combination of temperature and reduced oxygen available to the salmonella or other bacteria. Some bacteria cannot survive in a truly anaerobic atmosphere but salmonella, for instance, can withstand anaerobic conditions, although under such conditions they will not reproduce and in numbers may be reduced. Due to the fact that there is an oxygen component in the water, which is introduced in the products of combustion and there is oxygen in the feed stuff itself, it is difficult to obtain a truly anaerobic conditioning.
The foregoing illustrates limitations known to exist in present devices and methods. Thus, it would be apparent that it would be advantageous to provide an alternative directed to overcoming one or more of the limitations set forth above. Accordingly, a suitable alternative is provided including features more fully disclosed hereinafter.